com.triactive.jdo.store.sql.expr
Class AlternativesExpression

java.lang.Object
  com.triactive.jdo.store.sql.expr.AbstractSqlExpression
      com.triactive.jdo.store.sql.expr.BooleanExpression
          com.triactive.jdo.store.sql.expr.AlternativesExpression

All Implemented Interfaces:

SqlExpression, StatementTextGenerator

public class AlternativesExpression

extends BooleanExpression

A series of two or more boolean expressions combined with OR. Used by BooleanExpression to OR together any pairs of subexpressions (except for literals), with the result being that this expression is aware of the entire chain of adjacent OR alternatives. The purpose is to possibly reorder the subexpressions such that those which share the same set of unprotected outer join references will be grouped together and have protectOuterJoins() called just once for each group.

In other words, given a JDOQL filter such as:

 "mother.firstName == n || father.firstName = n || mother.middleName == n || father.middleName == n"
 

assuming "mother." and "father." require outer joins, then we can reorder the alternative subexpressions before adding the "IS NOT NULL AND" to generate more compact SQL:

 MOTHER.PERSON_ID IS NOT NULL AND (MOTHER.FIRST_NAME = ? OR MOTHER.MIDDLE_NAME = ?) OR
 FATHER.PERSON_ID IS NOT NULL AND (FATHER.FIRST_NAME = ? OR FATHER.MIDDLE_NAME = ?)
 

Author:

Mike Martin

Nested Class Summary

Nested classes inherited from class com.triactive.jdo.store.sql.expr.AbstractSqlExpression

AbstractSqlExpression.Body, AbstractSqlExpression.CompoundExpression, AbstractSqlExpression.SimpleColumnReference, AbstractSqlExpression.SubqueryExpression

Field Summary

Fields inherited from class com.triactive.jdo.store.sql.expr.AbstractSqlExpression

body, qs

Constructor Summary

AlternativesExpression(BooleanExpression operand1, BooleanExpression operand2)

Methods inherited from class com.triactive.jdo.store.sql.expr.BooleanExpression

and, eor, eq, ior, not, noteq, protectOuterJoins, unprotectedOuterJoins, unprotectedOuterJoins

Methods inherited from class com.triactive.jdo.store.sql.expr.AbstractSqlExpression

accessField, add, callMethod, cast, com, div, getColumnMapping, getJavaType, getMapping, getQueryStatement, getReferencedColumns, gt, gteq, innermostQuery, innermostQuery, lt, lteq, mod, mul, neg, newBody, newBody, newBody, newBody, newBody, newBody, newResultExpression, newSubqueryBody, select, setMapping, sub, toStatementText, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AlternativesExpression

public AlternativesExpression(BooleanExpression operand1,
                              BooleanExpression operand2)